$.fn.loading = function() {
	var f = $("<div class='loading-fixed'></div>").appendTo("body").css({
		position : "fixed",
		width : "100%",
		height : "100%",
		top : 0,
		left : 0,
		zIndex : 99999
	});
	$("<div></div>").appendTo(f).css({
		position : "absolute",
		width : "100%",
		height : "100%",
		top : 0,
		left : 0,
		backgroundColor : "#000",
		filter : "alpha(opacity=70)",
		opacity : 0.7
	});
	var loading = $("<img src='/resources/images/loading.gif' />").appendTo(f); //这里需要修改下图片路径
	loading.css({
		position : "absolute",
		top : $(window).height() / 2 - loading.height() / 2,
		left : $(window).width() / 2 - loading.width() / 2
	});
};
$.fn.offloading = function() {
	$(".loading-fixed").remove();
};